Field of the Invention
The present invention relates to wireless communication and, more particularly, to a method and apparatus for receiving a frame.
Related Art
In a wireless local area network (WLAN) system, a distributed coordination function (DCF) may be used as a method enabling a plurality of stations (STAs) to share a wireless medium. The DCF is based on a carrier sensing multiple access with collision avoidance (CSMA/CA).
Generally, in operations under a DCF access environment, when a medium is not occupied (i.e., idle) for a DCF interframe space (DIFS) interval or longer, an STA may transmit a medium access control (MAC) protocol data unit (MPDU) whose transmission is imminent. When the medium is determined to be occupied according to a carrier sensing mechanism, an STA may determine the size of a contention window (CW) using a random backoff algorithm and perform a backoff procedure. The STA may select a random value in the CW to perform the backoff procedure, and may determine a backoff time based on the selected random value.
When a plurality of STAs attempts to access a medium, an STA that belongs to the STAs and has the shortest backoff time is allowed to access the medium and the other STAs may suspend the remaining backoff time and wait until the STA that has accessed the medium terminates its transmission. When the STA that has accessed the medium terminates the frame transmission, the other STAs contend again with the remaining backoff times to obtain a transmission resource. As described above, in the existing WLAN system, one STA occupies all of transmission resources through one channel in order to transmit/receive a frame to/from an AP.